Visual fields are a spatial array of visual sensitivity. Visual fields are frequently assessed in vision research and in ophthalmology to determine vision loss and to diagnose diseases such as glaucoma and the like. For example, an ophthalmic perimeter (also referred to as a visual field perimeter) is a test device that can be used for these measurements. The ophthalmic perimeter typically returns sensitivity values for a set of isolated visual field locations. The minimum luminance required for the patient to detect the illumination is called the threshold sensitivity of that location. The reliability of each measurement may be estimated by global indices, such as the proportion of incorrect answers given by the patient during a complete perimetry exam.